Identifying the Genetic Basis of Schooling Behavior in Threespine Stickleback

The genetic changes that underlie the evolution of schooling behavior in teleost fish have yet to be understood. Previously, we used an artificial school of model fish to show that marine stickleback fish tend to school longer than freshwater fish, and differ in their relative body positioning. These two populations also show differences in their lateral lines, a sensory system that has been implicated in schooling behavior in other fish. We have used genetic mapping in marine-freshwater F2 hybrids to investigate the genetic basis for divergence in schooling and the lateral line. We found that a single genetic locus was responsible for differences in lateral line patterning as well as differences in schooling behavior, suggesting that these two phenotypes may be controlled by the same gene.  One gene within this genomic interval, Ectodysplasin (Eda), appears to be a good candidate for affecting lateral line patterning. To determine whether Eda or a neighboring gene is also responsible for variation in schooling behavior, current work is aimed at narrowing the genomic interval of the schooling behavior locus. To do this, we screened 320 hybrids using microsatellite markers to identify fish that were recombinant around the Eda locus. We phenotyped 111 recombinant F2s using the model school assay, in order to narrow the region of genotype-phenotype association in this region. Ultimately, understanding the genetic basis of social behavior, such as schooling in fish, is not only an important goal in animal behavior but also a crucial step to answering broader evolutionary questions.